Production of threads and the like



25 50% of the total solvent mixture with cellulose characteristic of theinvention, are in general 25 Patented June 23, 1936 I? 1 Q I IUNITEDVCI'STATVES "ZOIFFICE" No Drawing. Application October 17, 1932,Serial No. 638,177.; In Great Britain November 2, 1931 v I 12 Claims.(Cl. 18*54) This invention relates to the manufacture of may be of suchlow solvent power that its subseartificial filaments, threads, yarns,ribbons, films quent action on the filaments or other products and likespun products from solutions of organic does not materially decreasetheir covering power. esters of cellulose and especially celluloseacetate. When employing actone alone or acetone mixed In British PatentNo. 356,170 processes are dewith relatively small quantities of water,this phescribed for the manufacture of filaments and nomenon may detractsomewhat from the comother spun products from solutions of cellulosemercial valueof the products. esters of low degree of esterification i.e. esters The above spinning solutions may be spun by having less thantwo ester groups per cellulose dry or wet spinning methods. The spinningconmolecule CsHmOs. The said patent refers to disditions will, ofcourse, be adjusted in accordance 10 solving the saidestersin mixturesof acetone with with the nature of the product desired. 7 For Wate'rforthe purpose of manufacturing the spun example the spinning conditionsmay be adjustproducts. I I have now found that improved reed so as toobtain filaments of round cross-section sults may be obtained byemploying as solvent or of'relatively flat cross-section, or they may befor esters of low ester content, e. g. those deadjusted toobtain hollowor voluminous filaments, 15

scribed in the above-mentioned patent, mixtures it being, generallydesirable, in the case of dry of acetone or like ketone, which is asolvent for spinning, to increase the spinning temperature in the morehighly 'esterified cellulose, with alcothe neighbourhood of the spinningnozzles and/or hols, and especially methyl and ethyl alcohols, toincrease thev rate of flow of the evaporative 20 ith or without water,medium or the temperature of the spinning solu- 20 The proportion ofacetone to alcohol may vary tion immediately. prior to extrusion toachieve considerably and is to some extent dependent this latter result.--In dry spinning operations, the upon the ester content of thecellulose ester. The temperatures necessary to obtain a particularrealcohol may, for example, constitute as much as sult, employing assolvent mixture the mixture diacetates or cellulose acetates of slightlylower somewhat higher than those which may be used acetyl content.Usually good results are obtainto obtain similar products using acetoneor mixable with proportions of -40% of alcohol and tures-of acetone withsmall quantities of water. 70-60% of acetone." With an acetate of 52%Filaments prepared from the spinning solutions 30 acetyl content,somewhat less alcohol may be used. described herein may be stretched'inany suitable 30 The alcohol in the above mixtures may be partly manner,or maybe -shrunk, if desired, by any replaced by water. For example,with a cellulose suitable process. Such filaments may-also be acetatehaving an acetyl value of about 48% a submitted to partial or totalsaponifieation, or solvent mixture may comprise 60-75% of acetonetreated by processes calculated to modify their 20-35% of methyl orethyl alcohol and -5-10% of dyeing l properties. Processes according tothe water. Instead of acetone other ketones may be present invention mayalso be used in conjunction used as for example methyl ethyl ketone.with processes for reducing or modifying the Cellulose esters ofrelatively low ester content lustre of the filaments. for use in thisinvention may be prepared by any The following example will serve toillustrate 40 suitable process. Thus for example they may be theinvention, but it is not to be considered as 40 prepared by thehydrolysis (ripening) or .saponilimiting it in any way. 2182:2211; ofcellulose esters of relatively high ester Example Not only are theadvantages, and notably the Cellulose acetate of acetyl content 48%(calimproved moisture regain, exhibited by the filaculated as aceticacid) obtained by hydrolysis of 45 ments, threads and the like ofBritish specificaa cellulose acetate of higher acetyl value is distionNo. 356,170 also attained in the process acsolved to form a 25% solutionin a solvent mixcording to the present invention but in addition, tureconsisting of 70 parts of acetone, 25 parts inasmuch as it is possibleto replace far more aceof ethyl alcohol and 5 parts of water. The solu-50 tone by alcohol or by mixtures of alcohol and tion so obtained isextruded from suitable orifices water than is possible in the case ofwater only, into a heated evaporative medium such as air or considerableeconomies can be effected. Moreother gas maintained for example at atemperaover, I find that when spinning at high speed, ture of 7585 C.and the filaments thus formed for example 200-300 metres per minute ormore, are associated by twisting. I

the residual solvent mixture left in the filaments The invention isparticularly important in re- 55 lation to the spinning of filaments andlike products from cellulose acetates, but may also be employed for theproduction of filaments and other products from cellulose propionates,cellulose butyrates, cellulose formates, cellulose nitroacetates andlike organic esters of cellulose and mixed ether-esters of cellulosesuch as ethyl cellulose acetate and oxyethyl cellulose acetate.

What I.claim and desire to secure by Letters Patent is:-- r r 1. In aprocess for the production of artificial filaments, yarns, bristles,straw, ribbons and the like, which comprises spinning into a settingmedium a solution containing as sole cellulose ester an organic ester ofcellulose of relatively low.,de-

gree of esterification, the step oi forming said solution by dissolvingsaid organic 'ester of cellulose in a solvent mixture containing asubstance selected from the group consisting of acetone and methyl ethylketone, and an alcohol.

2. In a process for the production of artificial filaments, yarns,bristlesstraw, ribbons and the like, which comprises spinning into asetting medium a solution; containing as sole cellulose ester an organicester ofcellulose'containing less than two ester radicles per moleculeof cellulose considered as Cal-11005, the step .ofiorming said solutionby dissolving said organic ester'of cellulose in a solvent mixturecontaining acetone and a lower fatty alcohol.

3. In a process for, the production of artificial filaments, yarns,bristles, straw, ribbons and the like, which comprises spinning into anevaporative atmosphere a solution containing as sole cellulose estercellulose acetate containing less than two acetate radicles per moleculeof cellulose considered as CsHmOs, the step of forming said solution bydissolving said cellulose acetate in a solvent mixture :containingacetone and methyl alcohol. l .v

4. Process according to claim 3 wherein a cellulose acetate having anacetyl value of at least 40%, calculated as acetic acid, is employed.

5. Process according to claim 3 wherein a vcellulose acetate having anacetyl value of at least calculated as acetic acid, is employed.

6. In a process for the production of artificial filaments, yarns,bristles, straw, ribbons and the like, which comprises spinning into anevaporative atmosphere a solution containing as sole cellulose estercellulose acetate containing less than two acetate radicles per moleculeof cellulose considered as CcHmOs, the step of forming said solution bydissolving said cellulose acetate in a solvent mixture containingacetone and ethyl alcohol.

7. In a process for the production of artificial filaments, yarns,bristles, straw, ribbons and the like, which comprises spinning into anevaporative atmosphere a. solution containing as sole cellulose estercellulose acetate containing less than two acetate radicles per moleculeof cellulose considered as C6H1005, the step of forming said solution bydissolving said cellulose acetate in a solvent mixture containingacetone, water and methyl alcohol.

8. In a process for the production of artificial filaments, yarns,bristles, straw, ribbons and the like, which comprises spinning into anevaporative atmosphere a solution containing as sole cellulose estercellulose acetate containing less than two acetate radicles per moleculeof cellulose considered as Cal-11005, the step of forming said solutionby dissolving said cellulose acetate in a solvent mixture containingacetone, water and ethyl alcohol.

- 9. In a process for the production of artificial filaments, yarns,bristles, straw, ribbons and the like, which comprises spinninginto asetting medium a solution containing as sole cellulose. ester an organicester of cellulose having an acyl content below the minimum necessaryfor solubility in pure acetone, the step of forming said solutionbyldissolving said organic ester of cellulose in a solventmixturecontaining acetone and a lower fatty alcohol.

1.0. Ina process for the production of artificial filaments, yarns,bristles, straw, ribbons and the like; which comprises spinning into anevaporative atmosphere a solution containing as sole cellulosev estercellulose acetate having an acetyl content below the minimum necessaryfor solubility in pure acetone, the step of forming said solutionbydissolving said cellulose acetate in a solvent mixture containingacetone and ethyl alco-. hol. i

11. A spinning solution for the production of filaments, yarns,bristles, straw, ribbons, films and the like comprising an organic esterof cellulose of relatively low ester content ,dissolved in a solventmedium containing acetone and a lower fatty alcohol, said ester beingthe only cellulose esterpresent in the solution. ;12. A spinningsolution for the production of filaments, yarns, bristles, straw,ribbons and the like, which comprises a cellulose acetate contain: ingless than two acetyl radicles per molecule of cellulose, considered asCal-1100s, dissolved in a solvent mixture comprising acetone and ethylalcohol, said cellulose acetate being the onlycellulose ester present inthe solution. v

4 HENRY DREYFUS.

